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Move signal code into its own source file and add sudo_sigaction()

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wrapper that has an extra flag to check the saved_signals list to
only install the handler if the signal is not already ignored.
Bump plugin API version for the new front-end signal behavior.
This commit is contained in:
Todd C. Miller
2013-01-17 13:29:46 -05:00
parent 99704cc101
commit 855a11af2b
8 changed files with 229 additions and 140 deletions
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90
src/exec.c
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@@ -104,7 +104,7 @@ static int fork_cmnd(struct command_details *details, int sv[2])
* XXX - currently we send SIGCONT upon resume in some cases where
* we don't need to (e.g. command pgrp == parent pgrp).
*/
zero_bytes(&sa, sizeof(sa));
memset(&sa, 0, sizeof(sa));
sigfillset(&sa.sa_mask);
sa.sa_flags = SA_INTERRUPT; /* do not restart syscalls */
#ifdef SA_SIGINFO
@@ -113,11 +113,11 @@ static int fork_cmnd(struct command_details *details, int sv[2])
#else
sa.sa_handler = handler;
#endif
sigaction(SIGCONT, &sa, NULL);
sudo_sigaction(SIGCONT, &sa, NULL, false);
#ifdef SA_SIGINFO
sa.sa_sigaction = handler_user_only;
#endif
sigaction(SIGTSTP, &sa, NULL);
sudo_sigaction(SIGTSTP, &sa, NULL, true);
/*
* The policy plugin's session init must be run before we fork
@@ -175,56 +175,6 @@ static int fork_cmnd(struct command_details *details, int sv[2])
debug_return_int(cmnd_pid);
}
static struct signal_state {
int signo;
sigaction_t sa;
} saved_signals[] = {
{ SIGALRM }, /* SAVED_SIGALRM */
{ SIGCHLD }, /* SAVED_SIGCHLD */
{ SIGCONT }, /* SAVED_SIGCONT */
{ SIGHUP }, /* SAVED_SIGHUP */
{ SIGINT }, /* SAVED_SIGINT */
{ SIGPIPE }, /* SAVED_SIGPIPE */
{ SIGQUIT }, /* SAVED_SIGQUIT */
{ SIGTERM }, /* SAVED_SIGTERM */
{ SIGTSTP }, /* SAVED_SIGTSTP */
{ SIGTTIN }, /* SAVED_SIGTTIN */
{ SIGTTOU }, /* SAVED_SIGTTOU */
{ SIGUSR1 }, /* SAVED_SIGUSR1 */
{ SIGUSR2 }, /* SAVED_SIGUSR2 */
{ -1 }
};
/*
* Save signal handler state so it can be restored before exec.
*/
void
save_signals(void)
{
struct signal_state *ss;
debug_decl(save_signals, SUDO_DEBUG_EXEC)
for (ss = saved_signals; ss->signo != -1; ss++)
sigaction(ss->signo, NULL, &ss->sa);
debug_return;
}
/*
* Restore signal handlers to initial state.
*/
void
restore_signals(void)
{
struct signal_state *ss;
debug_decl(restore_signals, SUDO_DEBUG_EXEC)
for (ss = saved_signals; ss->signo != -1; ss++)
sigaction(ss->signo, &ss->sa, NULL);
debug_return;
}
/*
* Execute a command, potentially in a pty with I/O loggging.
* This is a little bit tricky due to how POSIX job control works and
@@ -288,7 +238,7 @@ sudo_execute(struct command_details *details, struct command_status *cstat)
* We block all other signals while running the signal handler.
* Note: HP-UX select() will not be interrupted if SA_RESTART set.
*/
zero_bytes(&sa, sizeof(sa));
memset(&sa, 0, sizeof(sa));
sigfillset(&sa.sa_mask);
sa.sa_flags = SA_INTERRUPT; /* do not restart syscalls */
#ifdef SA_SIGINFO
@@ -297,12 +247,12 @@ sudo_execute(struct command_details *details, struct command_status *cstat)
#else
sa.sa_handler = handler;
#endif
sigaction(SIGALRM, &sa, NULL);
sigaction(SIGCHLD, &sa, NULL);
sigaction(SIGPIPE, &sa, NULL);
sigaction(SIGTERM, &sa, NULL);
sigaction(SIGUSR1, &sa, NULL);
sigaction(SIGUSR2, &sa, NULL);
sudo_sigaction(SIGTERM, &sa, NULL, true);
sudo_sigaction(SIGALRM, &sa, NULL, false); /* XXX - only if there is a timeout */
sudo_sigaction(SIGCHLD, &sa, NULL, false);
sudo_sigaction(SIGPIPE, &sa, NULL, false);
sudo_sigaction(SIGUSR1, &sa, NULL, true);
sudo_sigaction(SIGUSR2, &sa, NULL, true);
/*
* When not running the command in a pty, we do not want to
@@ -317,9 +267,9 @@ sudo_execute(struct command_details *details, struct command_status *cstat)
sa.sa_sigaction = handler_user_only;
}
#endif
sigaction(SIGHUP, &sa, NULL);
sigaction(SIGINT, &sa, NULL);
sigaction(SIGQUIT, &sa, NULL);
sudo_sigaction(SIGHUP, &sa, NULL, true);
sudo_sigaction(SIGINT, &sa, NULL, true);
sudo_sigaction(SIGQUIT, &sa, NULL, true);
/* Max fd we will be selecting on. */
maxfd = MAX(sv[0], signal_pipe[0]);
@@ -560,15 +510,16 @@ dispatch_signals(int sv[2], pid_t child, int log_io, struct command_status *csta
saved_pgrp = -1;
}
if (signo == SIGTSTP) {
zero_bytes(&sa, sizeof(sa));
memset(&sa, 0, sizeof(sa));
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sa.sa_handler = SIG_DFL;
sigaction(SIGTSTP, &sa, &osa);
sudo_sigaction(SIGTSTP, &sa, &osa, false);
}
if (kill(getpid(), signo) != 0)
warning("kill(%d, SIG%s)", (int)getpid(), signame);
if (signo == SIGTSTP)
sigaction(SIGTSTP, &osa, NULL);
sudo_sigaction(SIGTSTP, &osa, NULL, false);
if (fd != -1) {
/*
* Restore command's process group if different.
@@ -603,7 +554,7 @@ dispatch_signals(int sv[2], pid_t child, int log_io, struct command_status *csta
}
/*
* Read pending signals on signale_pipe written by sudo_handler().
* Drain pending signals from signale_pipe written by sudo_handler().
* Handles the case where the signal was sent to us before
* we have executed the command.
* Returns 1 if we should terminate, else 0.
@@ -647,10 +598,11 @@ dispatch_pending_signals(struct command_status *cstat)
/* Only stop if we haven't already been terminated. */
if (signo == SIGTSTP)
{
zero_bytes(&sa, sizeof(sa));
memset(&sa, 0, sizeof(sa));
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sa.sa_handler = SIG_DFL;
sigaction(SIGTSTP, &sa, NULL);
sudo_sigaction(SIGTSTP, &sa, NULL, false);
if (kill(getpid(), SIGTSTP) != 0)
warning("kill(%d, SIGTSTP)", (int)getpid());
/* No need to reinstall SIGTSTP handler. */